Experimental data is presented that demonstrates very high resolving power in an Ebert-type spectrometer when the jaws of the entrance and exit slits describe perfect circles in the slit plane. An observed spectral resolution of 125 000 in visible light is reported with slits which are 10 cm long and have a 20-cm radius of curvature in a spectrometer of 2.25 meters focal length. Application to other optical systems is discussed and the relationship between the radius of curvature of the slit and the optical arrangement is presented.
WILLIAM G. FASTIE, "Experimental Performance of Curved Slits," J. Opt. Soc. Am. 43, 1174-1175 (1953)